Method of making sintered metal stencils



J. B. BRENNAN METHOD OF' MAKING SINTERED METAL STENCILS Nov. 6, 1951 Filed Feb. 24, 1945 Figi figg INVEN'TOR.

JOSEPH B. BRENNAN A TTOE/VEYS Patented Nov. 6, 1951 METHOD F MAKING SINTERED METAL STENCILS Joseph B. Brennan, Bratenahl, Ohio Application February 24, 1945, Serial No. 579,635

This invention relates to screen stencils and methods of making the same, and more particularly to screen stencils composed of metal or other relatively strong materials which are insoluble in water and ordinary organic solvents.

Screen stencils of this type are highly advantageous because of their durability, because they are not affected by the inorganic and organic solvents ordinarily used in the inks, enamels and the like which are applied by screen stencils and because their dimensions do not change with variations in atmospheric conditions. In these respects they are vastly superior to the usual silk screen stencils which are at present widely employed in the application of designs and decorations to surfaces.

The general objects of the present invention are the provision of durable and accurate screen stencils which can be manufactured readily and economically, and the provision of efficient and economical methods of making screen stencils. Further objects and advantages of the invention will become apparent from the following description of a preferred form thereof, reference being made to the accompanying drawings (which are necessarily somewhat diagrammatic, with thicknesses of materials and mesh of screens exaggerated) in which Figure 1 is a plan view of a completed stencil made according to the present invention; Figure 2 is arsection through the stencil of Figure 1 on a greatly enlarged scale, the section being indicated by line 2-2 of Figure 1; Figure 3 is a plan view of a silk screen stencil utilized in the manufacture of the stencil shown in Figure 1; and Figures 4, 5 and 6 are sectional views on an enlarged scale showing steps in the production of the stencil in Figure 1, the section being taken through the region indicated by the line 4-4 of Figure 3.

Briefly, an all metal screen stencil made according to a preferred form of my invention comprises a screen composed of laments yor wires of metal either Woven into screen form, or made up of one or more layers of parallel filaments with the filaments in different layers extending in different directions, or thin perforated metallic sheets. All of these various materials are intended to be included Within the term screen as it is used hereafter.k The openings in the screen are filled in with finely divided metal powder, the metallic particles being sintered together to bond them to each other and to the screen. The nely divided metal powder is applied in the form of a design to leave the openings unobstructed in the areas where it is desired Claims. (Cl. lol-128.2)

to apply pigment or ink to an underlying object when the stencil is in use. According to my preferred method, the metal powder is applied to the screen by producing a silk screen by the usual photographic process and then applying the metal powders to the metal screen through the silk screen. Thereafter, the metallic particles are sintered together by heating the metal screen and powder to sintering temperature, preferably with the screen and powder clamped between rigid, smooth plates to produce the requisite or preferred sintering pressure. These operations result in the production of a durable stencil, embodying an accurate design and having substantially smooth plane surface Vthroughout the lled in areas of the stencil.

Referring to the drawings, in Figure 1 a prefered form of stencil embodying my invention is indicated at I0. This comprises a screen II shown herein as a line mesh, woven screen composed of fine metal Wires.y The entire area of the screen, except for the design I 4 indicated herein as a letter B, is lled in with sintered metal powder as indicated atV4 I2. The drawing is shaded to show the surface of the metal powder in diagrammatic fashion, but the powders employed are preferably so ne that the filled-in areas appear substantially continuous and smooth to the naked eye. Any convenient metals may be employed both in the screen andoin the filling-in metal. For example, the screen may be composed of bronze, monel metal, stainless steel, aluminum or other metal or alloy wires.

Any readily available powdered metals may be? employed to fill in the openings in the screen. Preferably, both the screen and the filling-in metals should be such that they will resist corrosion by the ink, enamel or other materials with which the stencils are intended to be used. Thus, monel metal, tin, aluminum and its alloys, and variousY non-ferrous alloys may be employed. The sintering temperature of the filling-in metal should be lower than the melting temperature of the material of theA screen, and in some instances, it is preferable to employ materials such that the filling-in metal will be sintered or otherwise bonded to the metal of the screen. For example, bronze screens may be employed with finely divided bronze powders of similar composition, and stainless steel screens may be lled in with tin powders.

As shown on an enlarged scale in Figure 2,v

form to irregular objects to be decorated without;

damaging the screen or separating thelling-in metal from the screen.

The steps of my preferredlmethodofnmaking Furthermore, the fact that the sintered Thus the completed.

the screen stencils of the present invention are illustrated diagrammatically in Figuresf'to 6, 'l

inclusive. Preferably the powdered metal I2 is applied to vthe screen II/through a silk screen stencil indicatedv generally at I5'. Asshown in Figure 3, this may comprise a silk or.v other textile fabric screen Ist supported in aframe FI in conventional manner and bearing a gelatin or other collodial design I8. It will be noted thatthe design I8 is in e'ect aV negative of the Adesign- I4'i-n the compl'etedstencil ID; i. ve., in the complete-d, stencil, the design Il!L is notV filled in, Whereas? in the silk screen stencil the design I8 iscomposed of hardened gelatin or the like fillingv inthe interstices of lthe'rscreen I5 vwhile the remainder ofk the area" of the screen rI6 remainsopen. r The silkv screen may be produced byf'con- Ventional methods, photographicv methods being employed ordinarily in order to secure accuracy of reproduction, and correct detail.V Y

."The next step in the' process is to place the wire screen Il upon a rigid supporting plate composed of a metal having characteristics which Y enable it to withstand the heat of the sub- V sequent sintering operation, and then to superpose"the silk'screen stencil I5 -uponthe wire sc'reen II as shown in Figure 4. The silk screen may be clamped orV otherwise secured-in position and then the metal powder making up the filling-in metal I2 is applied through the screen tI-,fthe design I8 preventing` the vpowder from filling in the openings of. rthe screen IYI- in the portions thereof which are within the area of the design I4. The powder may be .applied either-A in vdry or paste form. Sufcient powder is supplied to ll the openingsv in the screen I I, and preferably the powder extends slightly above the wires of the screen as shown in Figure 5. This result. is readily obtained by the use ofl the silk screen stencil I5 and insures that in the completed article the screenY IIA will besubstantially completely enclosed .within the sin-tered metal as shown in Figure 2.

[After the metal powder has been applied, the

silk screen is carefully removed without disturby ing the metal screen II, leaving the parts as shown in Figure 5. The next step is to sinter the powdered metal to bond the particles to each other and to the material of the screen. This is preferably accomplished by applying a pressure plate 2 I, which may be similar to the plate 20, over the screen II and powdered metalV I2,

securing the plates together by any convenientV means so that pressure will be exerted upon the powdered metal during sinteringv and then heating the` assembly to sintering `temperature and maintaining-it at that temperature for a suicient time to secure the proper sintering Of the powdered metal. The sintering temperatures of various powders under various pressure conditions are known to those skilled in the art andv will not be set forth in detail here. Generally speaking, sintering temperatures are always below fusing temperatures, andthe higher the pressure employed, the lower the sintering temperature required. Y l The screen-stencil is completed when" the sintering operationr is concluded, fthe assembly permitted to cool and the stencil removed from between the plates 20 and 2|, although some materialsfmay,advantageously be subjected to heat lThe sin-tering operation, particularly when and exibility'to withstand the stresses ordinarily encountered in the usage of the screen stencils. The stencils are much more durable and resistant to wear than ordinary silk. screen stencils and Y are not effected by atmospheric changes.V The method insures the production of accurate sten- 1 cils by relatively simple operation, and the methf od is particularly Valuable-where it is necessary to make several-metal stencils bearing identical designs,V for in such -caserjit is only necessary to produce one silk-V screen stencil byv the conventional .photographic methods.v ys f Y y While 'I prefer to apply the powdered metal tov the inorganic screen by means @for through* a silk screen, other methods of Yapplication-may be employed. For example, where -ne detail and accuracy of production are not of Vutmost vim'- portance,i a simple pattern, may be cut out jof thin meta-land 'laid loverathe inorganic screen and then the powdered metal applied to .all of the areas of the screen exceptthose blocked by the pattern. In suchan event, I prefer to appl-yv the metal to the inorganic screen through another screen in'orderl tel obtain uniformity of thickness throughout, .v

Various other changesfand modifications lin-my invention will be apparent to those skilled inthe art. The method may be employed in the manufacture of screen stencils ,from other materials. For example, certain plastic materials maybe used" as filaments,` and vpowdered plastics may be used as filling-in materials, with metallic or other screens, and bonded or cured by heatY and pressure. It is therefore to be understood that my patent is notlimited tothe preferred form of the inventionrdisclosred herein or in `any man-i ner other. than `:by Vthe scope of the appended claims.V Y

I claim:` V1. The methodV includes the steps of providingka screen member in which substantially all of the openingsV are unobstructed, lling in some but not all ofV the openings of the screen member with powdered metal ina nely divided Vstate at a temperature below the melting point of the metal, leaving Y p treatment. If desiredthe stencilr may be mount- `17.5l ed ina conventional frame (not shown) for use.

f making screen vstencils which 4. The method of making screen stencils which includes the steps of providing a screen member, filling in some but not all of the openings of the screen member with a powdered material in a nely divided state at a temperature below the melting point of the material to provide a pattern, and subjecting the assembly to heat and pressure to bond the particles of powdered material to each other and to the screen.

5. The method according to claim 4 wherein the screen member comprises a layer of parallel, unwoven filaments.

6. The method of making screen stencils which includes the steps of producing a screen stencil carrying a design which is a negative of the design to be produced in the nal stencil, positioning a second screen in which substantially all of the openings are unobstructed on a supporting surface, positioning the negative screen stencil over the second screen, applying finely divided powdered material through the negative screen stencil and onto the second screen,

.whereby the openings in the second screen are blocked by powdered material except in the areas blocked off by the design in the negative screen in which areas the openings remain unobstructed, and bonding the particles of powdered material to each other and to the screen.

7. The method of making all-metal screen stencils which includes the steps of producing a screen stencil carrying a design which is a negative of the design to be produced in the metal stencil, positioning a metallic screen in which substantially all of the openings are unobstructed on a supporting surface, positioning the negative screen stencil over the metallic screen, applying finely divided powdered metal through the negative screen and onto the metallic screen, whereby the openings in the screen are blocked with powdered metal except in the areas blocked 01T by the design in the negative screen stencil in which areas the openings remain unobstructed, and sintering the particles of powdered metal to bond them together and to the metallic screen.

8. The method of making screen stencils composed of inorganic material which includes the steps of photographically producing a silk screen stencil carrying a design which is a negative of the design to be produced in the inorganic stencil, positioning a metal screen in which substantially all of the openings are unobstructed on a supporting surface, positioning the negative screen stencil over the metal screen, applying nely divided powdered metal through the negative screen stencil and onto the metal screen,

whereby the openings in the screen are blocked with powdered metal except in the areas blocked oir by the design in the negative screen stencil in which areas the openings remain unobstructed, and sintering the particles of powdered metal to bond them together and to the screen.

9.' The method of making screen stencils which includes lthe steps of producing a screen stencil carrying a design which is a negative of the design to be produced in the completed stencil, positioning a screen in which substantially all of the openings are unobstructed on a ii-at supporting plate, positioning the negative screen stencil over the screen, applying nely divided powdered metal through the negative screen stencil and onto the screen, whereby the openings in the screen are lled with powdered metal except in the areas blocked 01T by the design in the negative screen stencil in which areas the openings remain unobstructed, removing the negative screen stencil, applying pressure to the filled in screen by means of a pressure plate engaging the upper surface of the lled in screen, and subjecting the assembly of pressure plate, supporting plate and screen to heat sufficient to sinter the particles of powdered metal together and bond the powdered metal to the screen.

10. The method of making metallic screen stencils which includes the steps of producing a silk screen stencil carrying a colloid design which is a negative of the design to be produced in the metallic stencil, positioning a metal screen in which substantially all of the openings are unobstructed on a flat supporting plate, positioning the silk screen stencil over the metallic screen, applying nely divided powdered metal through the silk screen and onto the metallic screen, whereby the openings in the metal screen are filled with powdered `metal except in the areas blocked off by the colloid design in the silk screen in which areas the openings remain unobstructed, removing the silk screen, applying pressure to the filled in metallic screen by means of a pressure plate engaging the upper surface of the lled in metallic screen, and subjecting the assembly of pressure plate, supporting plate and screen to heat sufficient to sinter the particles of powdered metal together and bond the powdered metal to the screen.

JOSEPH B. BRENNAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 16,048 Scott Apr. 21, 1925 1,064,166 Pindikowsky June 10, 1913 1,220,850 Jacobs Mar. 27, 1917 1,706,038 Owens Mar. 19, 1929 1,819,927 Taylor Aug. 18, 1931 2,034,437 Kessel Mar. 17, 1936 2,213,237 Brennan Sept. 3, 1940 2,267,918 Hildabolt Dec. 30, 1941 2,277,107 Imes Mar. 24, 1942 2,316,768 Brennan Apr. 20, 1943 2,421,607 Fowler June 3, 1947 

1. THE METHOD OF MAKING SCREEN STENCILS WHICH INCLUDES THE STEPS OF PROVIDING A SCREEN MEMBER IN WHICH SUBSTANTIALLY ALL OF THE OPENINGS ARE UNOBSTRUCTED, FILLING IN SOME BUT NOT ALL OF THE OPENINGS OF THE SCREEN MEMBER WITH POWDERED METAL IN A FINELY DIVIDED STATE AT A TEMPERATURE BELOW THE MELTING POINT OF THE METAL, LEAVING THE REMAINING OPENINGS UNOBSTRUCTED TO PROVIDE A PATTERN, AND SINTERING THE POWDERED METAL TO BIND THE PARTICLES THEREOF TO THE SCREEN AND TO EACH OTHER. 